Not Applicable
Not Applicable
The invention relates to a tablet rotary compression press for the manufacture of multi-layered tablets.
Rotary compression presses for the manufacture of tablet-shaped compacts are known in most varied embodiments. The typical rotary compression press comprises a rotationally driven rotor including a die-plate and top and bottom ram guides for the top and bottom rams, which interact with die-plate bores of the die-plate. The rams are actuated by stationary control cams. The compression process proper is performed by means of upper and lower pressure rollers by which the rams are moved against each other for the purpose of compressing the tablet from a powdered material which was introduced into the die-plate bores before.
It is also known to manufacture multi-layered tablets by means of such presses. If these consist of two or more layers it is readily possible to effect a layer-by-layer compression by means of appropriate charging devices and compression stations. In some cases, however, tablets are formed which are joined to a previously compressed portion, a so-called core. The core may either be pressed into a single-layered or multi-layered tablet on one side or may also be encased. For this case, it is required for the pre-compressed core to be fed from outside and to be aligned towards the die-plate bore in order that it may be compressed together with the material already pre-compressed in the die-plate bore. EP 0 349 777 A1 has made known a device by which pre-compressed cores are inserted. The known device has a rotationally driven disk next to the rotor. The disk supports therein radially movable arms each of which is adapted to hold a core with the aid of vacuum devices. The arms are radially moved while the disk is rotating in correspondence to the rotor such that the arms are brought into coincidence with a die-plate bore each. The expenditure for a device of this type and also the space it requires are relatively large.
It is the object of the invention to provide a tablet rotary compression press in which the insertion device for the pre-formed compacts may be integrated in the rotary compression press.
In the inventive device, the rotor has circumferentially included thereon a ring-shaped support surface on which the compacts are deposited in a position approximately aligned towards the die-plate bores. The compacts can be separated from each other by means of an appropriate feeding device and can be fed by cycles in such a way that each of them, while being aligned towards the die-plate bores, comes to rest on the support surface. The latter may be provided with a suitable recess in which the compacts are retained and are prevented from slipping off or rolling off as a result of the centrifugal force. The inventive device also provides radial arms which, however, rotate with the rotor. The arms have two radially movable gripping portions which are adapted to be moved relative to each other. The gripping portions may be radially led to opposed sides of a compact resting on the support segment and may be moved together subsequently in order to grip the compact. Subsequently, the two gripping portions may radially be moved through a distance until the compact is above the die-plate bore. Then, the compact may be held in this position while the gripping portions will move apart again. Subsequently, the compact can be pressed by means of the top ram into the material which is in the die-plate bore already. The rotor has provided therein a stationary guide which has a first and a second guide cam the cam followers of which are interacted with by the gripping portions in order to grip a compact on the support segment, to bring it into alignment with the die-plate bore, and to release it again.
In the inventive rotary compression press, the insertion device for the compact or the cores is integrated in the rotor of the press. The arms and the guide of the arms form part of the rotor and are supported within the rotor. Therefore, the physical size of conventional rotary compression presses need not be exceeded.
Various possible ways are imaginable to grip the compact on the support segment by means of the gripping portions and carry it to the die-plate bore subsequently. A provision which is particularly easy, according to the invention, consists in that lifting means are associated with the support segment which lift the deposited compacts if they are between the gripping portions. In another aspect of the invention, the lifting means may have lifting pins which are actuated by a stationary control cam.
In another aspect of the invention, the stationary guide has a stationary disk in the rotor above the die-plate, which has guide grooves for the cam followers.
The gripping portions and their support, in turn, may be realized by designs of different types. According to the invention, one consists in that the gripping portions and the cam followers each are mounted on tube lengths which telescopically interact with radial bars which are fixed to the rotor in a radial direction.
In another aspect of the invention, it may be expedient that the arms be pivotally supported about a horizontal axis at the radial inner end and that another stationary guide be provided which lifts said arms via a predetermined angle of rotation of the rotor. The charging device is known to be stationary. It possibly obstructs the way of the arms which follow on. In order to overcome this obstacle, the arms may be pivoted up in the region of the charging device.